At the core of this slowdown is the expectation that 2014 will represent the first full year of decline in Apple iPad shipments. Both the iPad and the overall market slowdown do not come as a surprise as device lifecycles for tablets have continued to lengthen, increasingly resembling those of PCs more than smartphones.

"The tablet market continues to be impacted by a few major trends happening in relevant markets," said Ryan Reith, Program Director with IDC's Worldwide Quarterly Mobile Device Trackers.

"In the early stages of the tablet market, device lifecycles were expected to resemble those of smartphones, with replacement occurring every 2-3 years. What has played out instead is that many tablet owners are holding onto their devices for more than 3 years and in some instances more than 4 years. We believe the two major drivers for longer than expected tablet lifecycles are legacy software support for older products, especially within iOS, and the increased use of smartphones for a variety of computing tasks."

Among different form factors and product groups, significant advancements have been made recently by hardware manufacturers to advance the 2-in-1, or detachable, product category. Devices have become thinner, prices have come down, and more models are available. Despite these advances, shipments of 2-in-1 devices are only expected to reach 8.7 million units in 2014, which is just 4% of the total tablet plus 2-in-1 market. A large reason for the relatively small uptake has been consumer hesitancy around the Windows 8 platform, which the majority of 2-in-1 devices are built upon.

"We need to look at how the tablet ecosystem is answering these challenges, and right now we see a lot of pressure on tablet prices and an influx of entry-level products, which ultimately serves Android really well," said Jean Philippe Bouchard, Research Director for Tablets. "But we also see tablet manufacturers trying to offset this price pressure by focusing on larger screens and cellular-enabled tablets. The next six months should be really interesting."

Looking forward, the few unknowns that could impact overall tablet shipments are: the industry reaction to Windows 10; what Google does in this space with Android and Chrome OS; and Apple's rumored product line expansion. Despite all of these unknowns, it seems clear that consumers can be expected to hold onto tablets longer than smartphones.